Gaining a clearer understanding of material behavior has industrial implications.

“Microcracking occurs in all different kinds of manufacturing environments, particularly those that include large structures, such as aerospace and wind energy,” says Maiaru. “Companies would be interested in being able to predict if cracking occurs before the material enters production. This would help them save time and money and make higher quality parts.”

While Maiaru’s research is a fundamental science project, she hopes her work ultimately leads to the development of crack-free thermoset materials.

“Our ability to manufacture the next-generation of high-performance, lightweight, complex structures depends upon fabricating damage-free composites with enhanced mechanical properties,” she says.

Marianna Maiaru, shown at the laptop computer, leads a team of researchers at the University of Massachusetts Lowell who are developing software to predict microcracking in composites.

Photo Credit: Umass Lowell

Giving Wings to 4D Printing

Project: 4D Composite Printing

School: Concordia University

Location: Montreal

Principal Investigator: Suong Hoa

Several years ago, Suong Hoa heard a seminar on 4D printing from one of his peers at Concordia University that piqued his interest.

“He was using polymers with shape-changing properties that react to a particular stimulus, such as water or heat,” says Hoa, a professor of mechanical, industrial and aerospace engineering and co-director of the Concordia Centre for Composites. “The idea came to me that we could use 4D printing to make complex composite shapes without the need for molds.”

Since then, Hoa and students at the Centre for Composites have printed and tested various components, including an S shape and a leaf spring. Most recently, they manufactured and performed a feasibility study on adaptive compliant trailing edge (ACTE) morphing wings for unmanned aerial vehicles (UAV) that can replace the frequently used hinged wing flap with one that attaches to the main body wing. The 4D-printed ACTE wing has a flex angle up to 20 degrees.

“Our study shows that a UAV using this kind of wing can support a good amount of load for small or medium-sized vehicles,” says Hoa.

The 4D printing technology developed by Hoa takes advantage of the asymmetry of composite materials.

“Rather than looking at anisotropic properties as a liability, I viewed them as an asset,” he says. “We utilize those properties to make a shape without the need for a mold.”

Standard 4D printing is like 3D printing, however it changes material from location to location. In 4D printing of composites, the material stays the same within a layer, but the fiber orientation changes from layer to layer.